To reduce such an inconvenience that wheels are bounded by the acceleration of a towing device capable of rapidly following the lateral movement of a blade because the degree of completion of a movement device is low.

Equipment for towing a series of carriages of a sorting machine comprises the pair of wheels driven by the motors thereof. The wheels are engaged with the blade disposed on the lower side of the carriages. The towing wheels are allowed to move in the directions for moving closely to and away from the blade relative to the motors thereof. Thus, the inertia of the member to be moved according to the mis-alignment of the blade can be reduced.